The mechanism of the receiver response status report of Automatic Repeat request (ARQ) by an Acknowledged Mode Radio Link Control (AM RLC) entity in a 3rd generation mobile communication system includes three trigger patterns: periodic, Radio Link Control layer Protocol Data Unit (RLC PDU) missing detection, and receiving the Polling message of the sender. Acknowledgement (ACK) or negative is acknowledgement (NACK) messages are included in a status report, and there are three data packet formats: bitmap (BITMAP), list (LIST) and relative list (RLIST). Two mechanisms of forbidding polling and forbidding periodic polling are used to decrease the frequencies of the status report.
As to the trigger mechanism of the receiver response status report of Automatic Repeat request (ARQ) by an Acknowledged Mode Radio Link Control (AM RLC) entity in a 3rd generation mobile communication long term evolution system, the conclusion of current 3GPP is that a state report should be triggered after a receiver's polling message is received, while other trigger mechanisms are still under discussion. Existing schemes under discussion comprise a receiver gap detection mechanism, i.e., when a receiver detects a gap among serial numbers (serial number, SN) of a received RLC PDU, i.e., the SNs thereof are not continuous, a timer is set in terms of the RLC PDU corresponding to the SN at the gap, and a status report is triggered when the timer times out. For example, the receiver receives RLC PDUs with SNs as 1, 2, 5 and 6, which means that the RLC PDUs with SNs as 3 and 4 at the gaps have not arrived at the receiver yet, so timers are set in terms of the RLC PDUs with SNs as 3 and 4 respectively, if the RLC PDUs with SNs as 3 and 4 still have not been received when the timers time out, status reports will be fed back respectively, wherein status reports include the negative acknowledgement (NACK) information of the above-mentioned RLC PDUs with SNs as 3 and 4, i.e., the RLC PDUs whose feedback information is NACK are those missing RLC PDUs with serial numbers 3 and 4 in the status report.
The main objective of adopting timers is to avoid false NACK status reports, due to the possible delay caused by Hybrid Automatic Repeat request (HARQ) retransmission, or after an HARQ entity of a sender has failed in retransmission for the maximum allowable number of times, the AM RLC entity of the sender will be notified directly to retransmit a RLC PDU, and an AM RLC entity of a receiver may receive the RLC PDU retransmitted by the sender immediately after detecting a gap. Under such situation, the receiver AM RLC entity should not feed back a NACK status report immediately after detecting a gap, but set a timer to wait for a certain period of time, and not feed back the status report until confirming that the RLC PDU corresponding to the SN at the gap has not been received when the timer times out.
Disadvantage of this scheme is that a timer has to be set respectively for every RLC PDU corresponding to the SN at the gap, and the status reports are fed back respectively when the timers time out, so the multiple messages will occupy much radio resources and lead to low efficiency. HARQ adopts multi-channel parallel processes and, with poor radio link status under normal circumstances, this may lead to unsuccessful retransmissions of multiple HARQ processes, thus a receiver AM RLC entity may detect several continuous or intermittent gaps during a short time period while receiving RLC PDUs. Under such condition, if an AM RLC entity has been notified to perform retransmission by an HARQ of the sender, the receiver AM RLC entity may receive RLC PDUs corresponding to the above-mentioned SNs at the gaps during a short time period, therefore, it will lead to resource waste to set a timer respectively for every RLC PDU corresponding to the SN at a gap.